[PATCH] crypto: ecc: fix NULL pointer dereferencing in ecc_gen_privkey()

[Roman Smirnov]

ecc_get_curve() can return NULL. It is necessary to check
for NULL before dereferencing.

Found by Linux Verification Center (linuxtesting.org) with Svace.

Signed-off-by: Roman Smirnov <r.smirnov@xxxxxx>
Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
---
 crypto/ecc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/crypto/ecc.c b/crypto/ecc.c
index f53fb4d6af99..fd63e354895b 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -1471,9 +1471,14 @@ int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
 	const struct ecc_curve *curve = ecc_get_curve(curve_id);
 	u64 priv[ECC_MAX_DIGITS];
 	unsigned int nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
-	unsigned int nbits = vli_num_bits(curve->n, ndigits);
+	unsigned int nbits;
 	int err;
 
+	if (!curve)
+		return -EINVAL;
+
+	nbits = vli_num_bits(curve->n, ndigits);
+
 	/* Check that N is included in Table 1 of FIPS 186-4, section 6.1.1 */
 	if (nbits < 160 || ndigits > ARRAY_SIZE(priv))
 		return -EINVAL;
-- 
2.34.1